Inherent to the operation of a reciprocating internal combustion engine is the requirement that it have a valve or valves for reliably communicating a mixture of fuel and air into the engine cylinders and for subsequently exhausting the products of combustion. A concurrent requirement is that such valves open and close during the appropriate periods in the operation of the cycle. The valves must also provide for a tight seal when they are in a closed position.
The common approach to the valve requirements of the reciprocating internal combustion engine is the use of one or more spring-loaded, tulip-shaped valve structures formed from metal. Each valve head seats tightly into a tapered opening, or port, in the head wall of the engine cylinder to seal the cylinder. This requires that the valve head have a very precise shape, with low tolerance for deviation from the design specification.
The valve includes an elongated stem which moves reciprocally in a guide, which is comprised of a bore in the cylinder head. A spring fits around the valve stem and is attached to the top of the stem. The spring is in compression and exerts an axial force which, in the absence of an opposing axial force on the end of the valve stem, is sufficient to keep the valve seated.
The end of the valve stem abuts one end of a pivoting rocker arm. The other end of the rocker arm abuts the end of a push rod. The push rod is reciprocally moved axially by a solid lifter which rides on a cam lobe on a camshaft. The camshaft is rotated by the engine crankshaft by means of a reduction gear or a gear and chain arrangement. Rotation of the crankshaft is thereby mechanically translated into an axial force on the valve stem which opposes the spring force. The force translated through a push rod when the lifter is riding on the high point of a lobe on the camshaft is sufficient to overcome the spring force and unseat the valve by pushing it into the cylinder.
This type of intake and exhaust valve has been widely adopted as the solution for the valving requirements of the internal combustion engine primarily because of the relative ease by which adjustments can be made for wear, reasonable manufacturing costs, and the proven reliability of the design. However, the intrinsic disadvantages of such valves and the necessary compromises in engine performance occasioned by their use are numerous.
It would be a benefit, therefore, to have a rotary valve assembly and system which increases engine performance over those with the heretofore mention valves. It would be a further benefit to have a rotary valve system which would replace the cam, lifters or followers, pushrods, rocker arms, tulip valves, valve springs, valve seats and keepers. It would be a still further benefit to have a rotary valve system providing a single intake port and a single exhaust port for each engine cylinder. It would be a further benefit to have a valve assembly capable of withstanding the harsh environment of an internal combustion engine.